Pump devices for producing foam



SePt- 13 1955 J. E. GIBSON ET A1. 2,717,770v

PUMP DEVICES FOR PRODUCING FOAM Filed Jan. lO, 1952 20 Y /9 WZ/i1 5 25 Nif* PUMP DEVICES FR PRDUCING FDAM John Edwin Gibson and Alexander James Went, London, England Application January 10, 1952, Serial No. 265,787

Claims priority, application Great Britain January 15, 1951 4 Claims. (Cl. 261-28) rangement being such that when the pump is in operf ation the latter draws said mixture from the tank and draws air through the tank, the foam produced then issuing from the gauze-pack.

For a better understanding of the invention, and to show how the same may be carried into eiect, reference will now be made to the accompanying drawings, in which:

Figure l is a cross-sectional elevation of a pump device, and

Figure 2 is a view on II-II of Figure l.

The pump device shown in Figures 1 and 2 has a cylindrical chamber 1 in which a cylindrical rotor 2 is mounted. The rotor extends the length of the chamber (Figure 2) and the longitudinal axes of the chamber and the rotor are parallel, but not coincident (Figure l). The axis of the rotor 2 is so disposed in relation to the axis of the chamber 1 that a portion 1A of the inner wall of the chamber almost contacts the periphery 2A of the rotor 2. The rotor and inner wall of the chamber, where they are almost in contact, are close enough to provide a seal 3 extending the length of the rotor. Around the rest of the periphery 2A of the rotor there is a gap between the rotor and the inner wall of the chamber, the gap being largest opposite the location of the seal 3.

The rotor 2 has tive radially directed deep grooves 4 (Figure l) cut along generators of the curved surface thereof. The grooves 4 extend the length of the rotor 2. A vane 5 consisting of a plate is slidably located in each groove 4.

The rotor 2 is in the form of iive hollow segments 6 open at each end and each having a centrally positioned web 7 for strengthening puiposes. Each web 7 has a hole 8 therethrough.

An inlet 9 (Figure 2) in the form of a slot extending the length of the chamber 1 is cut in the wall of the latter. The inlet 9 commences at 10 (Figure l) slightly more than one vane pitch from the seal 3 and terminates at 11 one vane pitch after its commencement. The termination 11 is located at the bottom of a pump device.

A tank 12 open at the top 13 to the atmosphere communicates with the inlet 9. The top 13 of the tank 12 is above the commencement of the inlet 9 and the bottom 14 of the tank 12 is level with the bottom of the chamber. The tank 12 extends throughout the length of the inlet 9 and that side of the tank that is adjacent the inlet 9 is entirely cut away so that the tank 12 freely communicates with the inlet 9. An inlet conduit (not States Patent O ICC shown) from a constant head device (also not shown) leads into the top 13 of the tank 12. The tank 12 contains a curved guide plate 15 (Figure 1) which extends from one end of the tank to the other. The upper end 15A of the plate 15 is secured to that side of the tank that is remote from the inlet 9. The lower end 15B of the plate 15 is supported on feet 16 at the bottom of the tank 12 and adjacent the inlet 9. A hole 17 is formed in the bottom of the tank, underneath the plate 15.

The outlet 18 from the chamber 1 commences at the sel 3 and extends over almost two vane pitches from the seal 3 in a direction opposite to the direction in which the commencement 10 of the inlet 9 was measured from the seal 3. The outlet 18 communicates with a short upwardly extending conduit 19 which is anged at its upper end for enabling a exible pipe to be attached thereto. A plurality of gauzes forming a gauze-pack 2t) is secured across the conduit 19, the gauzes being placed one on top of the other and each gauze covering the bore of the conduit 19. The ganzes are separated from each other by rings acting as distance pieces.

A curved bar 22 extends across the inlet 9 and a further curved bar 23 extends across the outlet 18 of the pump device. These curved bars 22, 23 follow the curvature of the inner wall of the chamber 1 and serve to guide the vanes 5 whilst the latter are proceeding across the inlet 9 and outlet 18.

The pump device described above operates in the following manner.

The rotor 2 is rotated in the direction of the arrow 24, so that the outer edges of the vanes 5 proceed from the seal 3 to the inlet 9 and thence to the outlet 18. Water y containing a foam stabilizer is fed to the constant head device and from thence to the tank 12. As the rotor 2 turns, the vanes 5 move outwardly under centrifugal action until their outer extremities encounter the inner wall of the chamber 1 and the bars 22, 23. A mixture of water, foam stabiliser and air is drawn through the inlet 9 and is carried around the chamber 1 to the outlet 18 through which it is expelled. The mixture is then forced through the gauze-pack 20.

It is to be understood that the rate of llow of water and foam stabiliser to the pump device is dependent solely upon the constant head device and is irrespective of the speed of rotation of the rotor 2. Since the top 13 of the tank 12 is open to atmosphere, an increase in the speed of the rotor 2 will increase the amount of air drawn through the pump device but will not materially increase the amount of water and foam stabiliser forced through the pump device. The increase in the speed of the rotor, therefore, has the etect of increasing the proportion of air to liquid in the resultant foam. During operation of the pump device, considerable turbulence and mixing of the air and liquid in the tank 12 takes place on account of the rush of air into the tank 12.

The hole 17 remains open during operation of the pump device, the masking of the hole 17 by the plate 15 and the suction on the mixture iiowing through the tank 12 preventing loss of mixture through this hole. When the rotor 2 is stopped, all liquid in the pump device drains through the hole 17.

In a modified form of the pump device described above shutters (not shown), for example, of the iris type, may be provided in the conduit 19 immediately before (that is to say, on the pump side of), the lowest and the uppermost gauze. These iris shutters would operate in a similar manner to those used in optical apparatus for varying the sizes of apertures. In the present application the two shutters would serve to vary the effective cross-sectional area of the gauze-pack 20.

For the production of good foam it is necessary that the mixture flowing from the outlet 18 of the chamber Y3 1should'ow'full-bore-through-the'gauze-packO. When the rotor 2 is rotating at relatively low speeds, however, the mixture owing from the outlet 1'8 may not flow full bore th'rdugh the conduit 19. iris shutters wma, therefore;bealjusted'to receftheffeetr-ve' cross-sectional ar'eaof ine ganzepak 2o 10 sueh 'an extent that the mixture l'would new fu vbore through the ler'esesenti5I-.iai area ef Athe gauze-paek that 'reni-amati uncovered Vby the shutters. Kp A Themesh'es of the individual gau'zies in hegauzeipaek 20ti`nay differ. 'For examplejthelowerand 'upper 'ganzes may be of wid'e lmesh, whereaslthe'interhieiiate gaze's may be"of'ne"me sh f The Vgrooves'fi/vlnichsupplo'r't thevanes 5 ^'are"`11o`t hecessarily radially f'di'rec'te'd. They 'may be 'ararrge Ltarigentially to an imaginary ici'r'clefconcentric -`with 'the periphery of the rotor Vand 'of smaller 'diameter than that of the "i'otr. jBys'o'arrangiiig' tlesefgrooves, they ea'n becutdeeperthan when they areiadiallyfdireeted. By using 'deep 'grooyea "it"`wi1l 'be understood that the varies can be :more 'effectively supported Lthan when shallow grooves ar'e 'used Whenth'e deeper 'grooves vfare used it is preferable to provide L'some form 'fof Vguide 4r'n'e'an's for maintainingltheoiiter extre'rniti'esffthe vanesia'gainst the wallof the chamber.` Stich "guide rneans may, Yfor example, 'take the for'm'of 'acircular rib *at one v"end "of the chamber, the rrib being concentric with "the -cylindrical Vchamber and "engaging Vin -`slots cut in the ends of the vanes. y e

Deectors (not shown) maybje'provided withinthe conduit 19, on `the pump side vof the "gauzeipacki't, for spreading the mixture, emerging from the' outlet `18,ov'er the cross-sectional area of theg'auz'ema'ck 20. p

Thefbars A22 and 23 as showninthe drawings aferdisposed vertically, vbutitjis tobeniderstoo'dthatit may be advantageous 'to "position them diagonally ac'r'oss the inlet andoutlet respectively.

1. Pump 'means `for :producing lfoarnffr'om a :mixture of `-water and foam stabilizer -delivered to said '-piii'p means'by Va constant head 'device'of *knownconst'iction comprising 'a ihollow'cylindrical chamber 'mounted Jwith its tlongitudinal axis substatiallylhori'z'or'i'tal, af'rotdrof substantially the same *axial l'engrthf as *said iclja'rtiber *and supported lee ':entric`:`a1lytherein, plurality of varies ex- -tending along thelengthof said rotor, said -vanes being respectively located in longitudinally directed slots opening through the rotor periphery, an outlet for the pumped mixture at the top of said chamber, a conduit communieating with said outlet, a-gauze pack in said conduit, an inlet extending over the `len'gth o`f the chamber and from the bottom of 'The latter upwardly for 'atlea's'b'one vane pitch, a tank having a large opening in one side thereof registering with said "chamber in'le't to 'provide Vdirect unrestricted communicatin 'between said tank and chamber, inlet vmeans 'at lth'etop of said tank adapted 'to receive the delivery at a constant rate from said constant head device andalso iropita/idea ffree unrestricted air inlet and a plate in s'aidtank which inclines downwardly towards the bott'ornofFsaidaukiopening and is adapted to mask an open drainage hole for the pump means in the bottom of said tank.

-2.-'Pur"n`p 4means-a'eeording to 'elaiml lin which ksaid-'gauze pack is="closeft`o'said chamber'outlet to Vensure that mixed Water, 'ai'r'and stabilizer forced throughfth'e outlet by 'the va'n'es impin'ges dire'etlyat 'full -bore\o11-'the gauzepack.

3. Pump meansaselaime'tlin v`claim lin -which sectors of fthe `said frotor formed 4between -adjacent VAslots are hollowand are p'eniatleach en'd thereof.

4. --P`u'mp fmeans as -`laimed lin claim 1 in 'whi'eh the eecentricmounting f'lsaid'rot'orfpr'ovidesya line seal "b'etween the `roto`r Lperiphery and i chamber wall, which -se'al extends Lover the 'wholeffaxial :length lof "the 'rotor and fis located immediately `ft'nllowing said chamber outlet in the-V ope-a'tivedirection y-of rotation' of said Yrotor. 

